Process of filtering.



D STATES PATENT OFF MARK LAMB, OF SANTIAGO, CHILE, ASSIGNOR T0. ALIiIS-GHALMERS MANUFACTUR ING COMPANY, OF MILWAUKEE, WISCONSIN, A CORPORATION OF DELAWARE.

rnocnss or, FILTERING.

No Drawing.

To all whom it may concern:

Be it known that I, MARK R. LAMB, a I

citizen of the United States, residing at San:

use of a filter leaf and especially to the filtering of a solution of nitrate salt from slimes of the raw material in which it is found; and more generally it is concerned with the filtering of a solution of salts from go 'cake makingsame rotten.

slimes of the raw'material whereother salts are also present in the raw material.

The object of theinvention s to prevent the falling off of the cake of'residue from the filter leaf during the process of washmgn 'It is claimed and desired to thecake. g

It has been found that when' the nitrate deposits contain ,a great deal of foreign salt such as, for instance, sodium chlorid,. the cake formed on the filter consists sometimes ,of ten to fifty per cent. of sodium chlorid. If water is used as a Wash, the strength of the cake, or its resistance to deformation, is

soireduced that it falls from the leaf, This is because the fresh water removes a great Even if the cake, formed on the filter does not-become so rotten? as to cause the same to fall from the-leaf, it may become so piped as to draw all of the wash medium through the pipes and thus fail to remove the niter remaining the cake.

' In order to-overcome this objection it is proposed-to wash the cake with a solution of sodium chlorid. It is a well known fact that even a saturated solution of sodium chlorid is capable of taking up sodium. nitrate, so that when the wash water consists of such a solution of sodium chlorid the" remaining nitrates will be taken up by the solution without taking out any of the sodium chlorid in the cake or in other words,

Specification of Letters Patent.

Application filed June 22, 1914. Serial No. 847,138.

without rotting same, so that it will remain attached to the filter leaf during the process of washing, Usual. processes are, then employed for separating the sodium nitrate from the sodium chlorid.

It is intended that the scope of this invention is such as to include its application to. the Washing of a cake formed in the fil tering from slimes of raw material of a solution of any salt when said raw material also has a foreign salt commingled therewith. In any case the wash water will be a solution of the'foreign salt. The invention further applies to cases Where there is a plurality of foreign salts present in the rawmaterial, and in these cases the wash Water willbe a solution of all said foreign salts.

secure by Letters Patent,

'1. The process of removing a desirable substance from a filter cake containing said desirable and an undesirable'sub nce, by

washing the cake with a solution 0 the undesirable substance whereby the undesirable substance will remain? in said cake and prevent collapse of same.

2. The process of removing niter from a filter cake containing niter and av soluble foreign salt, by washing the cake with a solution of the foreign salt whereby the for eign salt will remain in said cake and prevent collapse of same. f I

3.-The process of removing niter from a filter cake containing .niter and sodium chlorid, by washing the cake with a solution of sodium chlorid whereby the sodium chlorid will remain in said cake and prevent collapse of same. i

In testimony whereof, the signature of the inventor is affixed hereto in the presence of R. LAMB. Witnesses two witnesses.

G. F. DE Wain. W. H. LIEBER. 

